The invention relates to apparatus for cutting elongated material into shorter lengths and the use of gas jets for uniformly removing the cut material. More particularly, the invention provides a means for avoiding any substantial increase in noise level ordinarily associated with the use of gas jets in this environment.
Cutters as described by Keith in U.S. Pat. No. 3,485,120 are broadly used for cutting tow into staple length fibers. These cutters include a rotatable reel having outwardly facing cutter blades against which the tow is wound and a fixed pressure roller pressing upon the tow wound around the reel resulting in cutting of the innermost layers of tow by the cutter blades. As cutting progresses a wad of cut staple fibers is forced inwardly between adjacent pairs of blades. Unfortunately, centrifugal forces and interfiber adhesion resist removal of wads of cut fibers by gravitational forces. Thus the wads of cut fibers continue to rotate with the reel and continue to increase in size until either the cutter jams or until chips of cohered staple break off from the wads and fall into the collection hopper. These chips provide low fiber openness and cause subsequent difficulties in mill processing.
Cook in U.S. Pat. No. 3,733,945 recognizes the problems of jamming the cutter and lack of staple openness using cutters described by Keith and as a solution to these problems Cook discloses mounting at least one fixed jet so that it jets air downwardly upon the proximity of the doffing point of the cut fiber through aligned apertures in the cutter reel which rotate past the jet. This assists the gravitational forces in overcoming the effect of centrifugal and fiber-to-fiber forces allowing the cut fiber to fall freely downward. However, Cook's arrangement has disadvantages associated with discontinuous passage of air from the fixed jet through apertures in the reel crossing through the air jet stream. Cook's arrangement is essentially that of a siren and as a consequence produces very high noise levels.